1. Field of the Invention
The present invention relates to an air bed conveying system for conveying workpieces such as sheet glass or the like in a floating condition within a heating furnace.
2. Description of the Relevant Art
Curved tempered sheet glass having a single curvature such as automobile side window glass, for example, is produced by floating-type curved sheet glass manufacturing apparatus which are high in productivity. Sheet glass which is produced by such an apparatus is conveyed with its lower surface held out of contact with the conveying mechanism. One conveying system for conveying sheet glass out of contact therewith is an air bed conveying system disclosed in Japanese Patent Publication No. 47(1972)-2110.
As shown in FIG. 10 of the accompanying drawings, a general air bed conveying system, which is not particularly disclosed in the above publication, includes an air bed 200 comprising a plurality of plate-like supports 202 set as boxes on a refractory furnace floor 201, and a plurality of bed blocks 203 placed on the upper edges of the supports 202. Each of the bed blocks 203 has a number of air ejection holes 203a defined therein all over its surface. The supports 202 and the bed blocks 203 jointly define a number of chambers which are supplied with hot air under pressure through ducts 204. The hot air supplied under pressure to the chambers is then ejected out through the air ejection holes 203.
Since the plate-like supports 202 are simply set on the furnace floor 201, the upper edges of the supports 202 for each of the bed blocks 203 may not lie flush with each other, preventing the bed blocks 203 from being placed hermetically on the supports 202. Therefore, the hot air kept under pressure in the chambers may leak out of the chambers through gaps that may exist between the supports 202 and the bed blocks 203, or may be ejected under irregular pressures from the air ejection holes 203. When such undesirable conditions occur, the sheet glass is not well floated over the air bed 200 or is not stably conveyed thereby. Another problem is that adjacent bed blocks 203 may not be vertically aligned with each other and hence may be vertically staggered with respect to each other.
The present invention has been made in an effort to effectively solve the problems of the conventional air bed conveying system.